This invention relates generally to computer systems and more particularly to clustered computer systems.
As is known in the art, a computer system is generally comprised of a central processing unit (CPU), a memory unit, at least one input/output device, and a bus which is used to connect the aforementioned devices. The computer is housed in a cabinet which contains a power supply to supply power for the various components of the computer. In operation, the central processing unit fetches and decodes incoming instructions, executes commands, and manipulates data, while the memory unit, which is composed of multiple storage locations, stores data to be used by the CPU. The I/O device is generally used to input data to and output data from the computer system. Typical types of I/O devices include printers, keyboards, displays and mass storage units such as disk drives etc. These devices are often interfaced to the computer-system with an I/O interface controller circuit.
Often, a user""s processing needs will grow beyond the capabilities of a single CPU. In an effort to meet these new processing needs, computers are typically clustered to make a plurality of CPUs available for processing. A clustered computer system is an integrated group of computers that communicate over a high-speed communication path. The clustered computer system acts as a single system to users. That is, clustered computer systems are characterized by a high degree of transparent resource sharing, which includes access by each individual computer system to storage located anywhere in the clustered system, and increased processing throughput.
In a typical cluster, there are two or more CPUs sharing inter alia at least one common system disk. Using multiple CPUs in a clustered configuration enables processing time on the CPUs to be used more efficiently. Thus, it affords the user better performance when jobs are run on a clustered system.
At least one additional general purpose computer is necessary to provide a clustered configuration for a computer system. Depending upon the characteristics of an existing system it may be possible to acquire an additional CPU and associated cabinet and power supply and interconnect these devices with the existing equipment. The two systems are connected through the additional cables and harnessing and are configured using software to behave as a clustered computer system. While the existing equipment and acquired general purpose computer system will provide a clustered computer system there are several drawbacks to this approach. For example, included with each general purpose computer system is a power supply and the cabinet as well as additional hardware such as cables and harnessing to connect the two computer systems. Clustering computer systems using this approach provides a redundancy in the hardware of the computer system, but at a substantial increase in cost particularly for the mechanical components necessary to provide the clustered system. Moreover, by providing separate cabinets, longer cables and harnesses are needed to interconnect the systems. This limits the maximum number of systems which can be interconnected, particularly for executing bus specification protocols, due to electrical timing and parameter considerations.
Another option available to provide additional processing power is multiprocessing. A single processing board can be used which includes multiple CPUs. This option however is not only costly but it assumes the user has foreseen a future need for an increase in processing power.
In accordance with the present invention, a general purpose computer apparatus includes a central processing unit, a main memory, and a system bus. The general purpose computer apparatus further includes means for interfacing the central processing unit to the system bus and means for interfacing the central processing unit to an I/O bus. The general purpose computer system further includes a housing enclosing the central processing unit, the main memory and the means for interfacing with the housing having a mechanical form factor corresponding to a disk drive housing with such an arrangement, the general purpose computer apparatus is housed in a chassis or housing which can be disposed within a disk drive slot of a standard general purpose computer cabinet. By appropriate interconnect and configuration of the apparatus with a second general purpose computer in the general purpose computer cabinet a clustered computer system can be provided.
In accordance with a further aspect of the present invention, a computer system includes a cabinet having at least one slot for receiving a disk drive, and a first general purpose computer apparatus disposed in the cabinet. The first general purpose computer apparatus includes a first central processing unit, a system bus, and an I/O interface module coupled to said system bus for interfacing said system bus to an I/O bus. The computer system further includes a second general purpose computer apparatus which includes a second central processing unit, a main memory, and means for interfacing the second general purpose computer apparatus to the first general purpose computer apparatus. The second general purpose computer apparatus further includes a housing enclosing the second general purpose computer apparatus, the housing having a mechanical form factor corresponding to the slot for receiving a disk drive, with the housing disposed in the slot. With such an arrangement a clustered computer system configuration may be provided by appropriate interconnect and configuration of the second general purpose computer apparatus with the first general purpose computer in the general purpose computer cabinet while saving the cost of an additional cabinet, power supply, cabling and harnessing. In addition, since the length of cabling will in general be shorter than prior approaches, more systems can be clustered on one bus. For example, if the systems are clustered over a DSSI bus, a total of eight systems may be clustered without violating electrical specifications for DSSI bus clusters rather than the maximum of three systems when the systems are housed in separate cabinets and longer lengths of cabling are necessary to interconnect the systems.
In accordance with a further aspect of the present invention, a computer system includes a cabinet for housing the computer system, the cabinet having a panel with at least two openings in the panel of the cabinet. The computer system further includes a power supply disposed within the cabinet and a first general purpose computer disposed within the cabinet. The first general purpose computer further includes a first central processing unit module, including a central processing unit, a main memory, an I/O adapter interface, and a system bus coupling the first central processing unit module to the main memory and the I/O adapter interface. The computer system further includes a disk drive disposed in a first one of the openings in the panel of the cabinet and a second general purpose central processing unit module disposed in a second one of the openings in the panel of the cabinet and coupled to the cabinet by the corresponding receiving means. The second general purpose central processing unit module further includes a control panel having at least one switch which is used to reboot the second central processing unit module. The first central processing unit module and the second central processing unit module receive power from the power supply. With such an arrangement the existing equipment may be connected to the general purpose central processing unit module to provide a multiprocessing system thus, saving the user the cost of a complete multiprocessing system as well as in some cases protecting an investment made in existing equipment.